Precision marine surveys for the engineering community

Chevron Pipeline

SURVEY OF BURIED PIPELINE ACROSS SACRAMENTO RIVER

Client: Chevron Pipeline Company

Completion Date: 2000

Contract Value: $120K

Chevron Pipeline Company transports aircraft fuel to Sacramento Airport through an 8”-diameter pipeline buried beneath the 7-mile wide Sacramento Delta. At 5-year intervals (1987, 1992, and 1997), Chevron Pipeline contracted Sea Surveyor to map the pipeline’s location and depth-of-burial as it crossed the Delta, the Deep Water Ship Channel, and several sloughs. A subbottom profiler used seismic reflection techniques to locate the buried pipeline and determine its burial depth. Divers used “jet probes” to directly measure the pipe’s depth-of-burial at selected locations to calibrate the seismic reflection data. A Class 1 hydrographic survey mapped the elevation of the seafloor over the pipeline.

Pipe in Subbottom Record

The pipeline was exposed by scour during the 1998 El Nino flood and damaged when struck by a ship’s anchor. Sea Surveyor provided emergency survey services to Chevron Pipeline Company, and located the exposed pipeline and ship’s anchor. Sections of the pipeline had been damaged by the ship’s anchor, dragged out of its trench, and were unsupported above the seafloor. Sea Surveyor provided navigation services to divers and contractors that recovered the anchor, repaired the pipeline, and covered the exposed pipeline with protective rock armor.

In 1999-2000, Sea Surveyor provided precision navigation services to assist a contractor that used directional drilling techniques to install a new pipeline across the Deep Water Ship Channel.